The baseball team you root for is probably not doing as well as you’d hoped this season.

That may seem to be a rash statement to make – especially for those who cheer for Washington, which is doing so well that it doesn’t even need a Joe Hardy this year.

But with 30 major league baseball teams battling 162 times a year, the odds are therefore 30-to-1 that your team will be the World Series champion.

Translation: fans of 29 teams are going to be disappointed come the end of October (or, God help us, the beginning of November).

Yeah, not every team can be as good as the Baker City Cougars. In 1933, they never lost a game.

Never.

Radio station WZBQ saw to that.

Confused? Then let’s have Tony Sportiello, the bookwriter of the new musical National Pastime, fill us in.

“Before 1933,” he says, “Baker City, Iowa did have a minor league baseball team – and when they did, local radio station WZBQ’s ratings soared. Then the team left, and the town was left with nothing. Considering that The Great Depression was on, times were really tough. The station greatly missed the ad revenue it got when the team played, but getting a new team to move to this little town seemed unlikely.

“So,” says Sportiello, after a quick smile comes to his face, “the people at the radio station invented a baseball team whose games they could broadcast. And to make sure that people kept tuning in, they made the Baker City Cougars a team that never lost a game.”

This is the premise of Sportiello’s National Pastime, the new musical for which he provided the book to Al (Sessions) Tapper’s music. New York gets to see it starting next week.

Considering how poorly the Yankees have done lately -- and how dully the Mets have done all season -- perhaps even their staunch fans will see the show instead of enduring their beloveds drop flies, blow leads and look awfully run down in run-downs.

Of course, at first glance, there seems to be a hole in Sportiello’s premise bigger than the one between left and center field. When people show up at Baker City’s stadium to see the Cougars, somebody’s going to notice that there’s no team on the field.

Sportiello smiles indulgently. “The Cougars are in Europe at the moment, playing all-star teams over there. No one in Iowa has the money during these hard times to go over there and see them play. See, the real story here is about a small town needing to survive. This can’t be a story about people who merely need to save their jobs or a radio station owner who wants success at any cost. It’s about saving the town.”

Every team needs a superstar, so the station invents Joe Miller, who’s already hit 500 home runs by the age of 23. Of course, listeners will want to hear post-game interviews with the legend-in-the-making. Now what?

Sportiello has an answer for that, too. He certainly knows his baseball, for he’s been a fan since his youth. “I was a big Baltimore Orioles fan growing up, even though I was living in Brooklyn” he says. “I used to listen to their games on the radio each night, picking them up from Baltimore. There was plenty of static, but I worked hard to hear what was going on.”

Actually, in the era in which Sportiello became an Oriole fan, the team was doing almost as well as the Baker City Cougars. They won consecutive pennants in 1969, 1970 and 1971.

“I was 11 when they won that first one,” he says. “And I was completely confident that they’d beat the Mets in the World Series.”

Even New Yorkers who weren’t alive then know that that didn’t happen. Mets in five.

Says Sportiello, “The Orioles losing after they were heavily favored gave me my first adult lesson: things don’t always work out the way you think they will. The Mets were the ones who taught me that bad things can happen in life.”

Around the same time, Sportiello was recruited by a sharp-eyed teacher who saw the lad’s ability to write, and commissioned him to create a play for his sixth-grade class. “I wrote one in high school, too,” he says, “and of course they were terrible.”

By this point, he’d become a fan of musicals. “My parents had all the records of the famous ones: My Fair Lady, Sound of Music, Show Boat, Oklahoma!” he proclaims. “I thought they were terrific, and played them all the time – even when my friends came over to play pool in the basement.”

The thought of it sends him into a momentary reverie as he recalls those days. “My friends were good about the records,” he says. “They didn’t complain much.”

So as a baseball and musical theater fan, Sportiello felt double the pain when his cherished Orioles were losing to the Mets in that final game and someone in the stands held up a sign that said, “Bye Bye Birdies.”

The genesis of National Pastime can be traced to 1993. Sportiello learned that the Hall of Fame in Cooperstown had a small theater on its premises, but that it was rarely used. As we all know, if you build it, they will come -- and Sportiello decided to come to Cooperstown with a one-act play.

“It was called Contract Time,” he reports. “A superstar has a mother who was a teacher and didn’t make much money. He decided that he shouldn’t get all those millions for playing. His agent is horrified.”

Contract Time went so well that Cooperstown asked for another play – and that’s what set the wheels in motion for the musical. It had a reading there in 2010; then National Pastime scored in our national capital at the Keegan Theater last year. Dan Van Why, who received a Helen Hayes Award nomination for his role as Joe Miller, reprises it here.

So whether or not Washington comes to New York to play the Yankees in the 2012 World Series, this hit musical from Washington comes to New York next week.

“The Yankees!” sneers Sportiello. “Don’t get me started. They should have moved Jeter to third when Alex Rodriguez joined the team. He’s the best shortstop in the American League, and he’s the one who should …”

National Pastime plays Aug. 8-25 at the Peter Jay Sharp Theater, Playwrights Horizons, 416 West 42nd Street, New York City. Performances are Mondays through Fridays at 7 p.m. with matinees on Wednesdays and Saturdays at 2 p.m. Tickets are $35. Call (212) 279-4200.